摘要:

The quantitative predictive abilities of derivative spectral analysis by using the zero-crossing point method were compared with the results obtained by the use of multivariate calibration methods. Mixtures of two pesticides, diuron and chlorpyrifos, were resolved by application of derivative spectrophotometry. Partial least squares (PLS-1 and PLS-2) and principal component regression (PCR), full spectrum calibration methods, were also applied, with previous optimization of the calibration matrix, using the absorption spectra and the first-derivative spectra. Both approaches were satisfactorily applied to the simultaneous determination of diuron and chlorpyrifos in synthetic mixtures. However, significant advantages were found in the determination of these pesticides in groundwater samples, previous solid-phase extraction with C18cartridges, by application of different chemometric approaches when the calibration matrix was performed using the first derivative of the absorption spectra.

ISSN:0003-2719    

DOI:10.1080/00032719708002807

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Impedance spectroscopy was used to study the corrosion of a nickel implanted steel sample. The dosaye was 5 × 1015ions/cm2and the energy of the nickel ions was 3 MeV. The data from a Simple Randies circuit (Rpand Cdl) were used to explain the corrosion changes observed in a NACE National Association of Corrosion Engineers) Brine solution (used to emulate geothermal brine conditions) at pH 2.0 and 25°C in an air saturated solution. Iron concentrations measured by Induction Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) were used to calculate corrosion rates at various time intervals. Impedance spectroscopy1,2is an electrochemical technique which can be used to monitor corrosion and to our knowledge it has not been applied to implanted materials.

ISSN:0003-2719    

DOI:10.1080/00032719708002808

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A C60modified carbon paste electrode(MCPE) was prepared and its electrochemical properties in tetrabutylammonium hydroxide/CH3CN/H2O solutions were studied. Two pairs of mono-electron quasi-reversible redox peaks were obtained and characterized. The experimental results revealed that this electrode had a good electrocatalytic reduction response for nitrobenzene in these conditions. The catalytic reduction current had a good linear relationship to the concentration of nitrobenzene. The linear range of nitrobenzene concentration was between 5.0×10−5∼6.0×10−3mol/L. The detection limit was 3.0×10−5mol/L.

ISSN:0003-2719    

DOI:10.1080/00032719708002809

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The mainstream (MS) and sidestream (SS) smoke of three types of popular Indian cigarettes, a brand of low tar Indian cigarettes, a brand of US cigarettes and two brands of popular Indian bidis were analysed for carcinogenic total particulate matter (TPM) and nicotine levels employing standard smoking conditions and/or modified smoking standards.

ISSN:0003-2719    

DOI:10.1080/00032719708002810

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A novel algorithm for assessment of chromatographic peak purity is proposed. The method is based on a recently developed orthogonal projection technique associated with matrices. The performance of the proposed algorithm is demonstrated by use of simulated spectrochromatograms and real data sets of liquid chromatography with photo-diode array detection. Advantages and drawbacks of the method are discussed.

ISSN:0003-2719    

DOI:10.1080/00032719708002811

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

ISSN:0003-2719    

DOI:10.1080/00032719708002796

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor